Thermally-operated switch



Dec. 7 192e. n 1,610,189`

G. H. WHITTINGHAM THERMALLY OPERATED SWITCH Filed DSG. l'. 1924 2 Sheets-Sheet l [NVE/WOR.

A fr0/MH.

Dec. 7 1926.

G. H. WHITTINGHAM THERMALLY OPERATED SWITCH 2 Sheets-Sheet f2 Filed Dec. 19, 1924 Patented Dec. 7, 1926.

UNITED STATI- 3s 1,610,189 lPATENT OFFICE.

GEORGE H. WHITTINGHAM, OF BALTIMORE, MARYLAND, ASSIGNOR TO MONITOR CON- TROLLER COMPANY, OF BALTIMORE, MARYLAND, A CORPORATION 0F MARYLAND.

THERMALLY-OPERATED SWITCH.

Application lcd December 19, 1924.

liquid causes the expansion of the liquid,

which,l in turn, expands the chamber, a part of the wall of the chamber being corrugated and expansible longitudinally. In the present invention, the thermostatic element is immersed in a liquid contained within an upright metallic tube which'is included in an electric circuit, and a radiator communicates with the upper and lower ends of this tube. The tube and radiator are filled with a suitable fluid, the arrangement bein such that when the tube is heated by the ow of electric current, the fluid 'within the tube andradiator will circulate upwardly through'the tube and thence downwardly Athrough the radiator to the lower end of the tube. The heat conveyed from the tube through the liquid to the thermostatic element will cause the latter to move and actuate a switch or perform any other desired function. A suitable valve is provided for controlling the rate of fiow ot fluid through the tube and radiator. The chief advantage of this arrangement is that the device can be used for currents of small volume by restricting or cutting off the flow of the fiuid, and for currents of relatively large volume, by opening the valve and permitting the fluid to circulate freely through the radiator. The device is particularly desirable tor use in connection with currents of large volume because the circulating fluid carries oft' the heat from the tube, and the'latter can be of relatively small dimensions.

ln the accompanying drawing,

Fig. 1 is a front elevation, partly in sec-A tion, of a thermostatic controllin device in which the thermostatic element 1s a corrugated tube lled with an expansible'liquid;

Fig.'2 is a side elevation of the same, looking from right to left, in Fig. 1;

Fig. 3 is a front elevation of a modied Serial N0. 757,008.

form of device in which the thermostatic element is a compound rod or strip exten-ding into the liquid in the heating tube and adapted tol operate a switch outside of the tube;

Fig. 4 is a side elevation of the device shown in Fig. 3, looking from right to left in the latter figure;

Fig. `5 is a front elevation, partly in section, of a thermostatic controlling device in which the thermostatic element is immersed in a liquid within the heating tube and an extension thereof, and is adapted to operate a switch immersed in the liquid;

Fig. 6 is a side elevation of the device shown in Fig. 5 looking from right to left in the latter figure; and,

Fig. 7 is a section on the line 7 7 of Fig. 6.

Referring to Figs. l and 2 of the drawing, a represents a suitable base of insulating material upon which are secured, one above the other, metal supporting posts b, b. The lower post 7) Yis formed with a .downwardly extending socket l, into which is fitted one end of a heating tube 2, the latter being of relatively thin metal, preferably of copper, and the post b" is provided with a vertical. opening 3, in which is fitted the upper end of the heating tube. A radiator, shown as a coiled metal pipe 4, has one end fitting within a lateral opening 5 in the post and registering with an opening 6- in the lower part of the heating tube. The upper end of the coil 4 is connected ,by an insulating joint 7 to a short section of tubing 8, which extends through a lateral opening in the post b and communicates with the opening or recess 3 in said post. into the upper end of the opening or socket 3 in the post b', and this valve is adapted to open and close the end 'of the pipe section or tting 8, according to the position in which the valve is set. As shown, the valve comprises a Sleeve 9a, which is cut diagonally as shown at 9b, so that when the sleeve is set in the position shown in the drawing, it will close the end of the iitting'S, and when turned through an angle of 180 the end of the fitting will be entirely uncovered, and at intermediate points said opening will be partly closed.

The thermostatic element, in this view, comprises a thin annularly corrugated metal tube o, closed at its ends and filled with an A valve 9 fits expansible liquid 10. This tube is centrally located within the heating tube 2 and is of considerably smaller 4diameter in order that the fluid d within the tube 2 may have ample room to circulate. lThe tliermostatic tube rests upon the bottom of the socket 1, and the upper end of said tube is connected to a rod 11 which extends through an opening 12 in a bushing 13 in the valve 9. 'lihis rod 1l serves Ato center the eXpansible tube c within the heating tube and it also serves as a means for operating the pivoted switch arm 14, having a contact member 15 which normally engages a stationary switch contact 16 on a post 17, which is secured to the base a. rihe switch arm 1li, as shown in the drawing, is pivotally connected to a metal bracket 18, arranged upon the post 5'.

An electric conductor is shown aty 19,`con neeted to the post Z), and a conductor 20 is shown connected to the post t. rlhe cui'- rent flows through from one of these conductors, say conductor 19. to the post thence through the wall et the heating tube 2 to the post b', and thence tothe conductor 20. The principal function of the apparatus is as an overload device for electric motors, and ordinarily the heating tube will be included in a variable power circuit.a `With the arrangement described, assuming the valve 9 to be open, or partly open, the current flowing through the heating tube will cause the fluid therein to rise in said tube and circulate downwardly through the cooling tube or radiator to the bottoni of the heating tube, and thus heat will be continually carried off from the heating tube. The heat in the circulating fluid, will affect the thermostatie element and the liquid within said element will, when heated to a predetermined degree, causes the expansion of said element and the consequent opening of the switch. By adjusting the valve 9 so as to close the connection to the radiator, the thermostatic element can be caused to :tunetion with a relatively small amount of current passing through the heating tube, and by completely opening the valve, the fluid will circulate freely and carry oli' heat from the heating tube so that the tnermostatic element will operate only when the'volume 0i current fiowing is relatively very large. By adjusting the valve to the intermediate points, so as to more or less restrict the vflow of huid, the thermostatic device may be caused to operate with various amounts of current flowing through the heating tube. I prefer to use, as a circulating medium, a free flowing, non-freezing liquid, although any suitable free flowing liquid will answer the desired purpose.

In Figs'. 3 and 4, the heating tube and radiator coil are mounted the same as in Fig. 1, but the thermostatie element, instead of being a corrugated tube, is a bar c which remise extends through a circular opening 21 in the head of a valve 22 in the post b. This bar, composed as usual of two dis-similar metals, has its lower end secured centrally in the base of the socket l, and th'e circulating liquid conveys the heat from the heating tube 2 to the bar. The upper end of the bar, as shown, is provided with acontact member 2 3, normally engaging a contact 2li, and when the bar is heated to a prede-l termined degree, it bends and moves the contact 23-away from the fixed contact 24. rEhe valve 22 is rotatable, as in Fig. 1, to regulate the rate et iow` of the circulating fluid andthereby to adjust the apparatus so that the thermostat will function with ditferent rates of current flow.

in Fig. 5, the heating tube 2a is supported by the posts and as in the previous igures. rlhis tube may be of any suitable shape in cross section, but as shown in Figs.

'5 to 7, the tube is rectangular. A. tube 2b fits into a socket 25 in the post b and communieates at its lower end with the tube 2a, ot' which it forms an extension. 1n these iigures, a stationary insulated switch contact 26 is mounted on the side wall of the tube 2b and the thermostatie element c2 is entirely immersed in the liquid and carries at its upper end a contact member 27, which normally engages the stationaryl Contact 26. lThe thermostatic element shown in this iigure, (5) comprises a rod or bar composed of dissimilar metals and it is secured at its lower end in the base ci the socket '1 of the post b. rihe radiator coil 4 is connected through the insulated joint 7 to the pipe.

section 8, and a valve 28, fitting in the upper end of the tube 2b, is adapted to open and close communication between the tube and coil at the end of the fitting 8.l lThe operation of this torni of device is the same as that shown in Figs. 2 and 3. ln Figs. `5 and 6, however, the switch which is controlled by the thermostat is within the tube and immersed in the liquid instead of being outside of the tube. The circulating liquid CZ. for the device shown in Figs. 5 and 6 is preferably a high flash mineral oil, and this oil not only serves to carry away the heat i'rom the heating tube but also to extinguish the arc between vthe switch contacts when iis the latter 'are separated by the thermostat. I

In all of the gures of the drawing, the

movable member of the switch is eleetricoil from the supporting post b so that the current, passingfrom one of the supporting posts to the other, will pass through the heating tube and iiotthrough the radiator coils The switch operated by the thermostat ordinarlywill be in a circuit which controls a tripping device for cutting o the flow of current through the heating coil when the current rises to a point which would cause the thermostat to actuate the switch.

l What I claim is:

1. A thermo-Siphonl system comprising an upright metal tube adapted to be connected in an electric circuit, a radiator communicating with upper and lower parts of said tube, a fluid adapted to circulate through said parts when the tube is heated, and a thermostat arranged within said liquid.

2. A thermo-Siphon system comprising an upright metal tube adapted to be connected in an electric fcircuit, a radiator communicating with upper and lower parts of said tube, a fluid adapted to circulate through said parts when the tube is heated, and a thermostat arranged within said tube.

3. A thermo-Siphon system comprising an upright metal tube adapted to be connected in an electric circuit, a radiator communicating with upper and lower arts o f said tube, a uid adapted to circu ate through said parts when the tube is heated, a valve for regulating the flow of said fluid, and a thermostat arranged within Said tube.

4. A thermo-Siphon system comprising 'an upright metal tube adapted to be connected in an eleet'ric circuit, a radiator communicating with upper and lower arts of said tube, a Huid adapted to circu ate through said parts. when the tube is heated, a ther-- mostat arranged Within saidl tube, said thermostat comprising a rod composed of dii'erent metals and having one end secured in the lower part of the tube, and a switch w adapted to be opened and closed byv said right metal tube adapted tobeconnected 1n` parts when the tube is heated, a thermostat arranged Within said tube, said thermostat comprising a rod composed of dierent metals and having one end secured in the lower part of the tube, and' a switch immersed within the liquid and adapted to be opened and closed by said thermostat.

6. A thermo-Siphon system comprising an upright metal tube adapted to be connected in an electric circuit, a radiator communicating with upper and lower parts of said tube, a liquid adapted to circulate through said parts when the tube is heated, a thermostat arranged within said tube, and a switch immersed in said liquid and adapted to be opened and closed by the thermostat.

7 A thermo-Siphon system comprising upper and lower metal supporting members adapted to be connected inan electric circuit, a metal tube connecting said members, a radiator communicating with upper and lower parts of said tube, said` radiator having an insulating joint, a liquid adapted to circulate through the tube and radiator when the tubey is heated, and a thermostat in said tube.

8. A thermo-Siphon system comprising upper and lower metal supportin members adapted to be connected in an e ectric circuit, a metal tube connecting said members, a radiator communicating with upper and lower parts of said tube, said radiator hav-l l iig an insulating joint, a liruid adapted to circulate through the tube an radiator when the tube is heated, a thermostat in said tube and a valve for regulatin the flow of liquid thtough the tube and ra iator.

' 9. A thermo-Siphon system comprising an upright metal tube, a radiator communicating with upper and lowerparts of said tube, a` liquid ada. ted to circulate through said tube and ra iator whenv the liquid is heated, aA thermostat arranged within said tube; and means for electrically heating said liquid.

In testimony whereof I hereunto aix i my signature. Y

GEORGE WHITTINGHAM. 

